Coexistence of LTE with ISM (Bluetooth®, Wi-Fi®, and the like) band technologies and GNSS is necessary to be provided as these are becoming very common combinations in mobile handsets. Each of these technologies is developed by different group to serve a specific purpose. Characteristics of each of these technologies are different. They operate in different frequencies, have different access mechanism, have different frame structure, and peak transmit power.
When all these technologies operate simultaneously in an adjacent band, (small separation e.g., <20 MHz) usually 50 dB isolation is required. However, small form factor of the UE provides only 10-30 dB isolation. As a result, the transmitter of one radio severely affects the receiver of another radio. For example, a small form factor of the UE may pose great challenge of interference from transmission of ISM technology to the receiver of cellular technologies such as LTE or WiMax. Similarly, the transmitter of cellular technology may cause severe interference to the ISM receiver. The main cause of in-device co-existence issues may be because of receiver blocking due to limited dynamic range of power amplifier, Analogue to Digital converter and out of band emission due to imperfect filtering.